The Templar is one of the Followers you can choose in Diablo III to help you through the single-player.
The Templar becomes available via a quest within the Cathedral level 3 while on the quest: Reign of the Black King. After entering this level, down the stairs is seen a ritual performed by six Dark Cultists.
Dark Cultists: "Ave, magistros. Ave, registrus. Ave, loedastus. Ave, mendaxas. Illius animos. Illius vellenas. Illius fortens."
You: "It takes so many cultists to hold this man? Who could he be?"
Dark Cultists: "Maintain your incantations! He will soon turn ..."
Warrior: "Your magic is weakening ... I am free! Now, back to my mission."
After killing all six Dark Cultists, a quest becomes enabled on the Warrior freed from their grasp. Later on, you can choose whether the Templar stays with you.
The Templar's Character/Skill window may be accessed by pressing "F" on your keyboard or by clicking the Templar icon located at the top-left corner.
The Templar window provides the following features:
Level and experience bar.
Armor Slots: Weapon, Shield, Neck, two Ring slots and a special slot.
The Follower Special Slot is unlocked when the follower reaches level 18. Check out the Follower Special items.
Under the Skills section you can choose one out of two skills. Players can unlock a new Templar skill every 5 levels.
Heal: Heals you or the Templar for 90 Life. Cooldown: 15 sec.
Intervene: Taunts enemies attacking you for 8 sec when you are at 75% on health.
Loyalty: Regenerates 2 Life per second for all allies near the Templar.
Intimidate: Enemy units are slowed by 80% for 3 sec when they hit the Templar. Does not stack with other slows.
Charge: Charges a target, dealing 150% weapon damage and stunning all enemies within 15 yards for 3 sec.
Onslaught: Delivers a massive blow to an enemy for 200% weapon damage plus 20-28 physical damage. Cooldown: 20 sec.
Inspire: Increase resource generation for all allies that the Templar is following.
Mana, Arcane Power, Hatred, Discipline, Fury and Spirit by +3 per second.
Fury and Spirit: +30% generated.
Guardian: When an ally of the Templar is low on health, the Templar will charge enemies near the ally, damaging enemies for 45-66 physical damage and stunning them for 3 sec. The Templar will also heal the wounded ally for 70-95 Life, and grant them 6 Life regeneration for 15 sec. Cooldown: 1 minute.
Only one skill per tier can be chosen, but players have the option to retrain the Templar for 750 gold. Click the Templar icon with the mouse's right button to access the retrain option. Retrain can only happen at the town.
It is also important to keep in mind when disenchanting a spear, neck, ring or shield with the Nephalem Cube for materials to consider giving it to the Templar or another follower as an upgrade. The Templar is your tank or healer. It's easy to forget, but always see your Follower as an extension of your character. Thus, upgrade him as you would your character.